1. Field
One or more exemplary embodiments relate to an anisotropically elongated thermoelectric material, a process for preparing the same, and a device comprising the anisotropically elongated thermoelectric material.
2. Description of the Related Art
The technical field of thermoelectric materials and devices has expanded significantly in recent years because of their potential use in efficient solid state cooling and power generation. Bulk thermoelectric materials are generally considered to be relatively inefficient for energy conversion or energy transport applications. However, with the advent of nanotechnology and better materials fabrication tools, artificially fabricated quantum confined structures, such as quantum wells, have shown promise for greatly increasing the thermal to electrical energy conversion efficiency of thermoelectric materials and devices.
In recent years, studies on these structures have shown a steadily increasing figure of merit (hereinafter referred to as “ZT”). Generally, the efficiency of a material's thermoelectric performance is quantified by the figure of merit ZT, where T is the temperature of operation, and Z (=S2σ/κ) where S is the Seebeck Coefficient (in Volts/degree K), σ is the electrical conductivity (in 1/W-meter), and κ is the thermal conductivity (in Watt/meter-degree K). The Seebeck Coefficient S depends on the density of state (“DOS”). For reduced dimensions, for example, in two-dimensional quantum wells or one dimensional nanowires, the DOS becomes much higher than the 3-dimensional bulk materials. The higher DOS thus leads to higher S and higher σ values. The thermal conductivity κ becomes smaller if the dimension involved is less than the phonon wavelength.
It is now commonly accepted that a high ZT, e.g., ZT>1, would result in thermoelectric materials useful for various applications such as heat recovery, space power applications, and an even higher ZT, e.g., ZT>3 would significantly stimulate technology replacement in devices such as power generators and heat pumps and other similar devices. It has also been found that dimensional restriction can lead to a much enhanced efficiency over traditionally used bulk thermoelectrics.
It would thus be beneficial to develop new and improved thermoelectric materials based on bulk processing of unique anisotropic-structured and one dimensionally confined nano configurations as described in the detailed description below.